I've used Clojure for:
- Scraping web pages
- Shell scripts
- Building websites
- Playing around with OpenGL
- Writing async webservers
- HTML Templating
- Running parallel tasks (fetching multiple URLs and process in parallel)
- Playing around with real time audio
That's the practical / fun stuff.
But Clojure has plenty of theoretical depth as well. Ideas that will become increasingly more relevant as the mainstream comes to really understand the potential of Functional Programming.
Which isn't to say Clojure is perfect. But it seems to me that it's built on a better foundation than most of what's out there.